(1) Field of the Invention
The invention is related to a drainage end cap device for draining fluid from a hollow space in a vehicle, comprising a mounting unit that is durably mountable in a super-imposed manner onto a drainage opening provided in an outer shell of a vehicle. The invention is further related to a drainage cap for draining fluid from a hollow space in a vehicle, and to an aircraft comprising a drainage end cap device.
(2) Description of Related Art
Hollow spaces in vehicles are generally subject to accumulation of liquid, such as condense water, which need to be drained from such hollow spaces in order to avoid a degradation of the vehicles, e.g. due to corrosion. In more specific cases, other liquids than condense water may ingress into respective hollow spaces. For instance, fuel may unintentionally ingress into hollow spaces that are existent in fuel compartments of vehicles adjacent to fuel tanks thereof. This ingressed fuel may evaporate, whereby explosive gases are created, so that the hollow spaces must not only be drained to remove the ingressed fuel, but also permanently be vented to prevent any accumulation of explosive gases. Consequently, by drainage and venting of the hollow spaces accumulation of explosive and/or inflammable fluids, i.e. gases and/or liquids, in the hollow spaces is prevented so that any potential fire or explosion risk can be prevented.
The document EP 1 084 952 A2 describes fuel tanks of an aircraft that is embodied as a helicopter, wherein the fuel tanks are provided with specific vent valves and venting channels, and wherein the vent valves are configured to prevent ingression of fuel from the fuel tanks into the venting channels. Nevertheless, even if these venting channels are considered as defining hollow spaces, the document EP 1 084 952 A2 does not describe particular drainage measures for these venting channels and further does not describe any means for drainage and venting of hollow spaces that are defined in the vicinity of the fuel tanks.
One basic solution for draining and venting hollow spaces of an aircraft consists in providing through holes, e.g. through a lower outer shell of a fuselage of such an aircraft, with one or more drainage channels leading into a respective hollow space. However, when providing a rotary wing aircraft, such as a helicopter, with corresponding through holes in a lower side of its fuselage defining an outer or bottom shell, water may ingress via these through holes into the respective hollow space depending on an underlying flight mode of the helicopter.
For instance, during hovering of the helicopter over water close to the water surface, spray water may occur in response to turbulences created by rotor downwash of the main rotor. The spray water may ingress via the through holes into the respective hollow space, which may thus be filled with water. This is particularly problematic in cases where the spray water is salty sea water that acts in the respective hollow space as an electrolytic solution triggering a very fast galvanic, corrosive reaction with metallic parts existing in the respective hollow space.
Furthermore, during ditching of the helicopter water would ingress into the respective hollow space via the through holes. A solution for avoiding such an ingression of water during ditching consists in providing corresponding through holes in the bottom shell with check valves consisting of a cap and a weir gate. These check valves are adapted to ensure ventilation of associated hollow spaces via the through holes during flight and to seal the through holes by a corresponding weir gate's lift when sufficient water pressure is applied to the weir gate during ditching of the helicopter.
However, these check valves are not suitable to avoid ingression of spray water into the hollow spaces, as such spray water would not apply a sufficient water pressure onto the weir gates. Furthermore, such check valves frequently comprise metallic components which are, as such, prone to corrosion, especially when in contact with salty sea water. Additionally, the metallic components may influence the electromagnetic compatibility of the helicopter, as they could be caught by radar. Moreover, such check valves frequently exhibit a comparatively huge installation height. Finally, such check valves would not operate successfully when the helicopter fuselage is exposed to icing conditions, because their movable components, i.e. the weir gates, could be frozen to a fixed position.
A more reliable solution for avoiding ingression of water into a hollow space defined in the region of a bottom shell of a helicopter consists in providing corresponding through holes in the bottom shell with manually lockable plugs, which can be opened manually on ground to drain fluids that were accumulated in the hollow space during flight. Such manually lockable plugs are relocked after a corresponding drainage operation and remain sealingly closed during flight.
However, such drain plugs are not admissible with respect to hollow spaces defined in the vicinity of fuel tanks in the helicopter according to the relevant EASA/FAR-certification regulations, as such drain plugs do not allow a permanent venting of the hollow spaces. As already mentioned above, such hollow spaces must be drained and vented permanently to prevent any accumulation of explosive and/or inflammable fluids in the hollow spaces in order to exclude any potential fire or explosion risk. A permanent drainage and venting does, however, not exist when the drain plugs are sealingly closed during flight.
Still other drainage and venting options are described in the documents DE 10 2005 003 436 A1, EP 0 556 765 A1 and EP 0 672 583 A1 in terms of drainmasts for aircrafts in general. These drainmasts are adapted for draining wastewater from aircrafts and are mounted integrally, i.e. as one piece to the aircrafts. However, these drainmasts have a comparatively huge installation height and are also not suitable to avoid ingression of spray water into associated hollow spaces provided in the aircrafts.
One possibility for avoiding such an ingression of spray water into hollow spaces defined in the region of a bottom shell of a helicopter could be the provision of an active ventilator with a protective cap. However, such an active ventilator would require an electric current for operation and needs to be protected itself against spray water and ingress of water. Furthermore, such an active ventilator is expensive and only suitable for venting and protecting against ingress of spray water, but not for drainage purposes.
The document FR 2 907 099 A1 describes a drainage end cap device for an aircraft with a drainage end cap that is provided with a drainage channel. The drainage end cap is removably mounted to a mounting structure that, in turn, is rigidly attached to a support structure, which is provided inside a fuselage of the aircraft. The mounting structure defines an attachment base that protrudes through an opening provided in the fuselage and the drainage end cap is removably mounted to the attachment base by means of screws.
The document US 2006/0273224 A1 describes another drainage end cap device for an aircraft with a drainage end cap that is provided with a drainage channel. A mounting structure is provided and rigidly attached to a fuselage of the aircraft, and the drainage end cap is removably mounted to the mounting structure and the fuselage by means of screws.
The documents EP 1 621 459 A1 and FR 2 971 485 A1 describe other drainage devices with drainage channels. In these drainage devices, the drainage channels are kinked with an angle of 90°.